Hi, To what has already been said I think the two round-robin articles are a must-read about this issue, as they compare refinement of neutron and X-ray data for a given (simple) compound. They are a bit old, especially by today's synchrotron standards, but are still very interesting :
1) J. Appl. Cryst. (1992). 25, 589-610 "Rietveld refinement round robin. I. Analysis of standard X-ray and neutron data for PbSO4" => http://dx.doi.org/10.1107/S0021889892003649 2) J. Appl. Cryst. (1994). 27, 802-844 "Rietveld refinement round robin. II. Analysis of monoclinic ZrO2" => http://dx.doi.org/10.1107/S0021889894000646 Jump to figure 6 of the first article if you haven't read them already and are in a hurry. Of course these articles are both worst-case scenari for the X-rays, as you want accurate oxygen positions beside one heavy (Pb or Zr) atom. It's also always interesting to point out the distribution curve on the _isotropic_ displacement parameters (article 1 fig 7) when you are tempted to to use anistropic ones. Vincent -- Vincent Favre-Nicolin Université Joseph Fourier ObjCryst & Fox : http://objcryst.sourceforge.net
